New discovery pushes back human history

August 17, 1995

From Correspondent Brian Jenkins

(CNN) -- Ever wonder where we, as humans, came from?
How about Australophithecus anamensis? It may be a mouthful,
but that's the name scientists have given to a recent
discovery that may provide a crucial link to the period where
Homo sapiens, or humans, split from apes.

Until recently, "Lucy" was the oldest known "link", however
loose, between ancient apes and the modern man or woman.
Paleontologists found her bones in Ethiopia two decades ago.
After receiving the name Lucy, scientists called her species
Australopithecus afarensis. She was a hominid species, and
footprints from the same species were later found in
Tanzania. The footprints dated human ancestry to about
three and a half million years ago.

But that has now changed. A team of scientists has
determined that a group of fossils can roughly date human
ancestry to four million years. The bones were discovered at
two sites near Lake Turkana in
Kenya over the past 30 years.
Scientist say that unlike "Lucy", this group of fossils are
from a different species of the hominid branch called
Australophithecus anamensis.

Professor Alan Walker of Pennsylvania State University
believes this discovery is very significant.

"It means that we can put back the origins of one of human's
particular attributes: walking upright on two legs." Says
Walker, "We can put that back another half million years."

The key find was made last year by Meave Leavey, the wife of
famed anthropologist Richard Leavey. She found parts of a
shin bone which connected to the knee and ankle. The shapes
indicate the animal walked upright. It weighed about 120
pounds, and unlike ape ancestors, would not have been able to
grasp a tree branch with its big toe. Therefore, even though
this animal was hairy and resembled apes, it's most likely a
predecessor of modern humans.

"Australopithecus were bi-pedal," says Professor Walker.
"They had ape-sized brains, small brains. They had very large
teeth with very thick enamel, but their canine teeth did not
project, so you didn't see fangs when the animal smiled,
opened it's mouth, or yawned. And the males were twice the
body size of the females.

"They had ape-sized brains... They had very large teeth with very thick enamel."

Alan Walker, Pennsylvania State University

While Meave Leavey's discovery was significant for the Homo
sapiens species, another recent discovery has added to the
overall hominid branch. A species called "ramidus" was
identified last year. It goes even further back on the
hominid branch of the primate family tree. This revelation
came from fossils in Ethiopia that has been dated at nearly
four and a half million years. But ramidus was recently
reassigned to a new genus: Ardipithecus. Scientists believe
it may have been a separate branch that died out, and is not
a link to modern man.

So Australopithecus anamensis remain the most important
recent discovery. It means an identification has been made
of a hominid that existed between the time of ramidus and the
age of Lucy. This bolsters the belief that several types of
hominids roamed Africa as far back as four million years ago.

And scientists say more discoveries may be yet to come.
There is active paleontology now being conducted in both
Kenya and Ethiopia. That means right now, there is a better
chance of finding a more comprehensive documentation of the
critical phase between ramidus and Lucy. Such findings would
further the quest to pinpoint how long ago hominids split
off from apes and began the evolution towards the humans we
are today.